Conventional metal cutting shears have been used in industry for many years. It is widely recognized that among substantial drawbacks of this tool are: a short life span, relatively heavy weight and difficulty to operate, especially when a wide angle of an opening between the cutting edges is required.
Conventional metal cutting shears are usually manufactured with the blades permanently attached to hand levers. If at least one blade of such shears is ruined, the entire hand tool becomes unacceptable for further use and should be discarded. One way to solve this problem is to provide the shears with removable blades. An example of such metal cutting shears with removable blades is described in U.S. Pat. No. 2,801,468 to Anderson. In view of the removable nature of the blades, the life span of the Anderson tool is longer than that of the conventional shears with the permanent blades. However, each Andersen blade is designed with only one cutting edge and should be completely replaced a soon as such single cutting edge is ruined.
Furthermore, in some instances removal and replacement of the blades in the Andersen patent could be time-consuming and expensive in view of the plurality of the fasteners used for connection between the jaws and the blades.
To alleviate the above drawbacks, the present invention provides a removable blade with two cutting edges designed in such a way that while one blade is used, the other is kept protected within the interior part of the lever. The second blade can be easily substituted for the first one when it is necessary.
Furthermore, in the present invention the shears are designed to prevent the blades from sliding out from their engagement with the jaws. In view of that, the need for additional fasteners for connection between the blade and the jaw is substantially reduced.
Still further, this invention provides for a novel way of operating the metal cutting shears at a wide angle opening between the cutting edges.